In the field of telecommunications, wires used to carry the telecommunications signals are susceptible to noise from a variety of sources, including neighbouring wires in the same cable which may introduce near-end crosstalk (NEXT) or far-end crosstalk (FEXT), and nearby cables which may introduce alien crosstalk (AXT). As data transmission rates increase, the effect of this noise on error rates also increases.
Various attempts have been made in the past to minimise noise in telecommunications signals. For example, in twisted-pair cabling used in telecommunications networks, adjacent pairs in the cable generally have different twist rates, and the pairs may be individually shielded from electromagnetic interference using foil. The collection of pairs in the cable may be further shielded using a foil screen. This type of cable generally includes a grounding wire, also called a drain wire, to provide a grounding for the cable.
Typically, cables of the type described above are used to cross-connect telecommunications equipment at a premises. This may take place via patch panels which may include front and rear connection locations.
Another type of cabling system, known in the art as a “patch-by-exception” system, has hardwired cross-connections between connection modules to electrically connect ports of a data or voice switch/router with end user equipment. The connection modules generally include insulation displacement contacts (IDCs) onto which wires of respective twisted-pair cables are terminated to form the cross-connections, and the IDCs may include a spring contact which can be separated to break the connection. This type of connection module is sometimes known as a disconnect module. For example, the spring contacts may receive electrical contact-bearing fingers of a printed-circuit board (PCB) of a patch cord, for example of the type shown in PCT application PCT/EP2007/006369 (WO 2008/119370), the contents of which are hereby incorporated by reference in their entirety. The ends of such a patch cord may be plugged into the disconnect modules at any desired pair of locations in order to divert the data or voice signal from its original hardwired path to a new path between the desired pair of locations, thus creating a patched configuration which is an exception to the original (default) hardwired configuration.
It would be desirable to provide a patch-by-exception system with decreased susceptibility to electromagnetic interference, or at least to provide a useful alternative.